Michitaka Sakai attends Tokise High School as a student and member of the koto club. He possesses short pink hair and brown eyes, standing at 164cm at the series start, making him the shortest boy before Atsumu Yoshinaga's arrival. His standard outfit is the Tokise High uniform, worn seasonally; during warmer weather, he often leaves his shirt unbuttoned over a colored T-shirt.

Within the koto club, he interacts with members like Kota Mizuhara and Chika Kudo, who frequently tease him about his weight. This teasing, combined with his discomfort sitting seiza for koto practice, fuels his considerations of dieting. Michitaka experiences emotional vulnerability, particularly evident when Natsu Momoya suggests simplifying his sheet music to match his playing ability, hurting his feelings—though they later reconcile after Momoya apologizes. He is also deeply moved to tears witnessing his younger siblings' growth.

His food preferences include stomach-filling meals, while he dislikes cotton candy. Alongside Saneyasu Adachi and Kota Mizuhara, Michitaka is identified as a former delinquent prior to joining the koto club.